Caracterização de uma aldo-ceto redutase relacionada a patogenicidade de Xylella fastidiosa / Characterization of a pathogenicity related Aldo-keto reductase from Xylella fastidiosa

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The Xylella fastidiosa genome program generated a large number of gene sequences that belong to pathogenicity, virulence and adaptation categories from this important plant pathogen. One of these genes (XF 1729) was described in the genome annotation as being a phenylacetaldehyde dehydrogenase. However, the XF 1729 primary sequence analysis showed similarities to Aldo-keto reductase superfamily proteins. The AKRs are NADPH-dependent oxidoreductases structurally and functionally related. In this work, the similar sequence XF 1729 from Xylella fastidiosa was cloned onto the pET32Xa/LIC vector in order to over-express a recombinant His- Tag fusion protein in E. coli BL21(DE3). The expressed protein in the soluble fraction was purified by immobilized metal affinity chromatography (agarose-IDA-Ni resin). Secondary structure contents were verified by circular dichroism spectroscopy. Small-Angle X Ray Scattering (SAXS) measurements furnish general structural parameters (the particle radius of gyration of 27.5:J::0.8A and the particle maximum dimension of 90A) and provide a strong indication that the protein has a monomeric form in solution. Also, ab initio calculations show that the protein has some similarities with a previously crystallized aldo-keto reductase protein. The recombinant XF1729 purified to homogeneity catalyzed the reduction ofDL-glyceraldehyde (Kcat 2.26 S-I, Km 8.20:J:: 0.98 mM) and 2-nitrobenzaldehyde (Kcat 11.74 S-I, Km 0.14:J:: 0.04 mM) in the presence of NADPH The amino acid sequence deduced from XF 1729 showed the highest identity (40% or higher) with several functionally unknown proteins. Among the identified AKRs, we found approximately 29% of identity with YakC (AKR13) from Schizosaccharomyces pombe, 30% and 28% with AKR11A and AKR11B, both from Bacillus subtilis, respectively. The results establish XF 1729 as the new member of AKR family, AKR13B1. Finally, the first characterization by gel filtration chromatography assays indicates that the protein has an elongated shape, which generates an apparent higher rnolecular weight. Since Xylellafastidiosa 9a5c strain (associated with CVC) is the first plant pathogen to be fully sequenced, a large benefit for the whole field of disease research can be expected. An initial step has been taken towards the characterization the protein function encoded by its genes

ASSUNTO(S)

xf1729 gene proteina akr13b1 aldo-keto reductase gene xf1729 aldo-ceto redutase akr13b1 protein xylella fastidiosa

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